mash: Migrate shelf menus to wm common types

ash/sysui/context_menu_mus.h

Index: ash/sysui/context_menu_mus.h
diff --git a/ash/sysui/context_menu_mus.h b/ash/sysui/context_menu_mus.h
index bd41702e48fd91425cd9cf6190e741806961cc63..38b864f68011cace61aef4a4a89841340af6f9e2 100644
--- a/ash/sysui/context_menu_mus.h
+++ b/ash/sysui/context_menu_mus.h
@@ -11,14 +11,14 @@
 
 namespace ash {
 
-class Shelf;
+class WmShelf;
 
 // Context menu for mash.
 // TODO(msw): Mimic logic in LauncherContextMenu.
 class ContextMenuMus : public ui::SimpleMenuModel,
                        public ui::SimpleMenuModel::Delegate {
  public:
-  explicit ContextMenuMus(Shelf* shelf);
+  explicit ContextMenuMus(WmShelf* wm_shelf);
   ~ContextMenuMus() override;
 
   // ui::SimpleMenuModel::Delegate overrides:
@@ -35,7 +35,7 @@ class ContextMenuMus : public ui::SimpleMenuModel,
     MENU_CHANGE_WALLPAPER,
   };
 
-  Shelf* shelf_;
+  WmShelf* wm_shelf_;
   ShelfAlignmentMenu alignment_menu_;
 
   DISALLOW_COPY_AND_ASSIGN(ContextMenuMus);